What's cheaper to run ?

[kind_cir]

What would be cheaper to run ? A 5m runabout fitted with a 80hp conventional 2 stroke doing 25knts at WOT. Or the same fitted with a 100hp cruising at a lower RPM to achive the same 25knts.
Given all things the same just different hp ratings, which would sip less juice for the same speed ?

[Blackened]

G'day

My votes on the 100hp

Dave

[Lancair]

Theres a great thread (http://www.fishnet.com.au/forums/viewtopic.php?t=78136&postdays=0&postorder=asc&start=0&f=0) over at fishnet where people have submitted their outboards speed and fuel usage figures and TheJetster (username) has made a graph.

Andrew

[tuna boy]

im with dave..........its the 100hp for me

[Scott nthQld]

I think it would depend on the respecting engines. Are they the same size block to begin with?

But without knowing anything else about the engines, my money would be on the 100hp, lower revs, engines not working as hard, so it seems pretty simple.

[Noelm]

I would be thinking that the difference would be almost not measurable, you have a bigger Engine that will use more fuel than a small one, but it is going slightly slower, so it will even out, this is why, it will take X amount of power (power = fuel use) to make a certain Boat attain a set amount of speed, just can't get around that,

[Mtx]

will you stick to 25 knots with the 100hp?
or will you drive it at WOT.

I think the 100 would end up costing more because you will not contain yourself to 25 knots

[Roughasguts]

I think your 80 Hp needs some work if all it can do at wot is 25Kts.

But if you compare it to a say 3.0 litre Pajero and a 3.5 litre Pajero and theres probably about the same diferance in Hp. Then the 3.5 litre uses more fuel than the 3.0 litre but on the other hand goes better, until it's plug service and timing belt change time. Then I' ll stick with the 3.0 litre.

But with Outboards 2 bangers! I think once you hit 100Hp the fuel bill goes up and stays there. If you wan't economy go lower than 100 Hp.

[ifishcq1]

I did the swap last year and the saving in fuel going from an 85 2st to a 1004st is about 30% the extra speed is bugger all but it maintains speed through swalls where the old 85 didn't the revs don't vary that much and as for high fuel usage I get around 2.8km/ltr over a day including trolling and wot runs.. this is better than I get from my 4.1tinny with a 35 evinrude... go the 100 you will not be dissapointed as long as your hull can take the extra 50+kg if it can't then check the new di 2st s they use about the same fuel as the 4st but a bit snappier

SL